Bituminous paving mix

ABSTRACT

A street-covering mix comprising crushed gravel, sand, bituminous binding agents, and a filler with a plurality of components; the proportions of gravel, sand and bituminous binders comprise the greater amount, as used in fluid asphalt and asphalt beton, the proportion of filler being decreased; at least one component of the filler being selected to increase the structural viscosity of the mastic formed from the filler and bituminous binding agent.

0 United States Patent 11113,615,804

[72] Inventors Hans Peter Defregger [56] References Cited Muniqh; UNITED STATES PATENTS 12 2,841,060 7/1959 Coppage 106/277 x 21] A 1 N 2 3' 2,884,841 5/1959 Dickinson 106/281 x P 3,206,174 9/1965 Young 106/281 ux [22] Filed Dec. 30, 1968 3,287,146 11/1966 Rogers et al.. 106/281 [451 Patented 1971 3 457 090 7/1969 Sor et a1 106/281 [73] Assignee Walter de Couet Strabenbau und Tiefbau 32] Priority Jan. 9, 1968 Primary Examiner-Julius Frome [33'] Germany Oct. 1, 1968, P 18 00 147.3; Assistant Examiner-Joan B. Evans [31 1 Luxembourg Jan. 9', 1968, 55,238 A'wmey0tw John M 11111 [54] PAivING MIX ABSTRACT: A street-covering mix comprising crushed o gravel, sand, bituminous binding agents, and a tiller with a plu- [52] US. Cl 106/281, raiity of components; the proportions of gravel, sand and bitu- 94/20, 94/23, [06/282 minous binders comprise the greater amount, as used in fluid [51] Int. Cl ..C08h 13/00, asphalt and asphalt beton, the proportion of filler being C08h 17/10, C08h 17/16 decreased; at least one component of the tiller being selected [50] Field of Search ..106/273-284; to increase the structural viscosity of the mastic formed from the filler and bituminous binding agent.

BITUMINOUS PAVING MIX BACKGROUND OF THE INVENTION Description of the Prior Art For the purpose of paving, the prior art normally uses asphalt-concrete or poured asphalt. These two street-covering methods differ in their compositions principally by the amount of the mastic used, the mastic being a mixture of the filler and bitumen. For the relatively inexpensive method of producing asphalt beton paving by spreading and rolling, approximately half as much mastic will be used as in the production of a molten fluid asphalt, which is twice as expensive. Because of its high constituency of mastic, fluid asphalt has a higher tensile strength and cohesiveness, is nevertheless less stable and resistant to flow, and therefore not as rigid. By the definition filler" material is meant a material which has a granular size of less than 0.09 mm.

SUMMARY OF THE INVENTION The present invention has as its object the production of a street covering or paving of a great strength, which on one hand is as tough and has as much impact strength as fluid asphalt, and on the other hand is as hard and inexpensive to produce as asphalt beton.

In an attempt to achieve this object, one could employ only half as much mastic in the production of fluid asphalt, so that the fragmented gravel and sandy grains of the mineral foundation touch each other directly, as is the case with asphalt concrete. This kind of procedure, however, cannot be permitted since this method would involve a decrease in the proportion of bituminous binding agents, which would lead to a higher rate of the mortar-type corrosion and would lead to the washing out of the sand. For the reduction of the amount of mastic by retention of a sufficient proportion of bitumen, the filler amount is being decreased according to the invention and the resultant undesired fluidity of the mastic is being compensated for by the use of a filler with a plurality of components, of which at least one has the property of increasing the structural viscosity of the mastic, i.e. such viscosity, which is identified in consideration of the fact that the mastic is not of Newtonian fluid.

It has been established that the tensile strength of the street covering obtained is that much greater the better the mastic fills the existing hollow spaces between the mineral framework of gravel and/or sand, and the smaller the remaining space is. With the filler of the present invention, one can increase the filling of the pores and even approach the value of nil of the hollow spaces whereby the properties of fluid asphalt are approximated, although the mass remains grainy as in asphaltconcrete. Thus, a street covering is obtained that combines the viscosity of fluid asphalt with the hardness of asphalt beton.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood from the following specification.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The inventors discovered that when the ratios of crushed gravel, sand and bituminous-type binders, conventionally employed in the production of molten asphalt and of asphalt beton are maintained, a decrease of the conventionally employed amount of filler, a substitution of at least one component of the filler with a clay, treated with a wetting agent and finally the inclusion in the filler as a component, an organic compound with chain-forming molecules of the caoutchouc or synthetic polymer types, each step or means independently or in the combinations stated will improve the desirable properties of the coverings.

By such means particularly the structural viscosity of the mastic is increased. The ratio of filler to the covering is defined as between 6 to 20 percent, advantageously 10 to percent and preferably about 12 percent.

The wetting agent is to be selected among organic wetting agents for the treatment of the clay admix. I

As a component which aids the structural viscosity of the mastic preferably a fibrous structure is to be employed, preferably of the mineral fiber types.

The inventors discovered that a proportion of from 6 to 20 percent filler, particularly between 10 to 15 percent and preferably 12 percent, is desirable.

To increase the structural viscosity of the mastic, a preferable illustrative example of the foregoing invention employs in the filler components of organic clays treated with wetting agents.

It has also been proven favorable to employ a component selected among fibrous structures such being particularly suitable because the matting of the individual fibers brings about an especially good stiffening of the mastic. In particular, mineral fibrous materials such as asbestos, glass fiber and basalt wool have shown to be suitable.

Generally, in accordance with the invention, the following mixture for street covering employing mineral fibrous materials is preferably used.

about 2.5% Mineral fibrous material about 5.0% Limestone or slate powder about 3.9 Fine sand (0.09 mm. to 0.2 mm.) about 0.023% Wetting agents about 7.5% Bitumen about 46.0% Crushed gravel-size about 2 to 8 mm. about 35.0% Sand-size about 0.09 mm. to 2 mm.

In accordance with the invention, for the production of an especially elastic covering, as for example, the surface of tennis courts, preferably a filler component for increasing the structural viscosity of the mastic is selected from organic compounds with chain-fonn molecules; for example, caoutchouc or synthetic polymers.

The following mixture employing caoutchouc was discovered to be particularly suitable for a street covering:

about 0.4% caoutchouc particles about 7.1% limestone or slate powder about 3.9% fine sand (0.09 mm. to 0.2 mm.) about 0.023% wetting agents about 7.5% Bitumen about 46.0% crushed gravelsize about 2 to 8 mm. about 35.0% sand-size about 0.09 mm. to 2 mm.

Various modifications are contemplated and may be obviously resorted to by those skilled in the art without departing from the spirit and scope of the invention, as hereinafter defined by the appended claims, as only preferred embodiments thereof have been disclosed.

We claim:

1. A street covering mix comprising crushed gravel, sand,

' bituminous binding agents and a filler with a plurality of components, the proportion of the tiller being below 20 percent by weight of the total mix; at least one component of the filler being selected to increase the structural viscosity of the mastic formed from the filler and bituminous binding agent, aid mix 2. A street covering such as for a tennis court comprising about 0.4% caoutchouc particles about 7.1% limestone or slate powder about 3.9% fine sand 0.09 mm. to 0.2 mm. about 0.023% wetting agents about 7.5% Bitumen about 46.0% crushed gravel-size about 2 to 8 mm. about 35.0% sand-size about 0.09 mm. to 2 mm.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,615,804 Dated October 26. 1971 Inventor(s) Hans Peter Defregger, et. a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet [73] "Walter de Couet Strabenbau and Tiefbau" should read Walter de Couet Strassenbau and Tiefbau Signed and sealed this 19th day of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents RM F'O-105O (IO-69) USCOMM-DC OOB'IG-PGD a u s sovzmmzm PRINTING orrlci: lBli o-ul-su. 

2. A street covering such as for a tennis court comprising about 0.4% caoutchouc particles about 7.1% limestone or slate powder about 3.9% fine sand 0.09 mm. to 0.2 mm. about 0.023% wetting agents about 7.5% Bitumen about 46.0% crushed gravel-size about 2 to 8 mm. about 35.0% sand-size about 0.09 mm. to 2 mm. 